1. Field of Invention
This invention relates to solubilization chromatography, and more particularly, to improvements in the apparatus for performing solubilization chromatography.
In the solubilization chromatography process a solvent, consisting of a buffer solution and ionized micells, is allowed to flow through a capillary tube having two ends thereof connected, respectively, to the plus side and minus side of a direct current electric source, and then a sample is introduced into the capillary tube. Components of the sample are separated by the combined effect of the dissolution phenomenon of the sample in the ionized micells, and the capillary electro-phoresis. The components of the sample are analyzed qualitatively and quantitatively.
2. Discussion of the Prior Art
FIG. 1 depicts a known solubilization chromatography apparatus comprising a capillary tube 1 constiituting a column (made of, for example, fused silica), containers 2,3 each having contained therein a mixed solution of buffer solution and micells with the ends of capillary tube 1 being separately inserted into the containers. The micells are, for example, colloid ions formed by dissolving sodium dodecyl sulfate (SDS) in the buffer solution. Electric source E has a plus side connected to an electrode 4 disposed in container 2 and a minus side connected to an electrode 5 disposed in container 3, and used to apply voltage to both ends of capillary tube 1. A detector 6, such as an ultraviolet spectrophotometer, is disposed on capillary tube 1 at a portion near electrode 5 of the minus side of source E.
As shown in FIG. 2, two phases of micells and buffer solution flow through capillary tube 1 having such configuration. Thus, when high voltage is applied to tube 1, the buffer solution flows in the direction of arrow A due to electro-osmosis flow. On the other hand, dissolved SDS (i.e. micells) is anions and, due to electrophoresis, has properties to transfer to a direction toward the plus side which direction is opposite to the direction of flow of the buffer solution. However, since the transfer velocity of the buffer solution is larger than that of micells by electro-phoresis, SDS micells, eventually, arrive at container 3 (minus side) after the buffer solution.
If a sample SM is injected into the plus side (i.e. where electrode 4 is located) tube 1, having the flow of the two phases within it, a component of the sample (which component is not soluble at all in the micells) is carried on an electro-osmosis stream, and it together with the buffer solution transfers to the minus side (i.e. where electrode 5 is located in container 3) at the fastest speed.
On the other hand, a component of the sample (which component is dissolved completely in the micells) transfers at the same speed as that of the micells and is delayed most in arriving at the minus side (i.e. where electrode 5 is located).
Moreover, an intermediate component of the sample (which component is soluble in the micells to some extent) transfers at a medium level of speed.
As a result, each component of the sample being transferred in capillary tube 1 has a retention time corresponding to a difference in solubilization ratio. Thus, if the thus separated components of the sample are detected by a detector 6, disposed on the outlet side of capillary tube 1, a chomatogram corresponding to the solubilization ratio of each sample component is obtained.
However, to carry out accurate analysis with such conventional apparatus, a constant quantity of sample is introduced into tube 1. This is done by controlling the quantity of sample introduced into tube 1 by setting a difference in height between containers 2 and 3 and using the head (i.e. pressure) difference thus created. However, with such a method, it is necessary to lift the sample container to obtain a desired head difference and also the work required is inefficient and unreliable in result. Furthermore, in the process of lifting the sample container, capillary tube 1 is often moved. Thus, it is difficult to reliably reproduce the measurements with such apparatus. In addition, disadvantageously, it is necessary to change the quantity of introduced sample, depending on the separation capacity of the capillary tube 1. Thus, it is difficult to control accurately the quantity of injected sample.
Accordingly, there are still many disadvantages and deficiencies in the prior art involving apparatus for practicing solubilization chromatography